Thermal Analysis; Figure 14-4. Analysis Heat Sink Dimensions; Table 14-1. Case-To-Ambient Thermal Resistance - Intel Pentium Pro Family Developer's Manual

THERMAL SPECIFICATIONS
14.2.

THERMAL ANALYSIS

Table 14-1 below lists the case-to-ambient thermal resistances of the Pentium Pro processor for
different air flow rates and heat sink heights.

Table 14-1. Case-To-Ambient Thermal Resistance

Airflow (LFM):
With 0.5" Heat Sink 2
With 1.0" Heat Sink 2
With 1.5" Heat Sink 2
With 2.0" Heat Sink 2
NOTES:
1. All data taken at sea level. For altitudes above sea level, it is recommended that a derating factor of
1°C/1000 feet be used.
2. Heat Sink: 2.235" square omni-directional pin, aluminum heat sink with a pin thickness of 0.085", a pin
spacing of 0.13" and a base thickness of 0.15". See Figure 14-4. A thin layer of thermal grease (Thermo-
set TC208 with thermal conductivity of 1.2W/m-°K) was used as the interface material between the heat
sink and the package.
0.150"

Figure 14-4. Analysis Heat Sink Dimensions

Table 14-2 shows the T A required given a 29.2W processor (150 MHz, 256K cache), and a T C
°
of 85 C. Table 14-3 shows the T A required assuming a 40W processor. Table 14-2 and Table
14-3 were produced by using the relationships of Section 14.1.3., "Thermal Resistance" and the
data of Table 14-1.
14-4
°
Θ CA [
C/W] vs. Airflow [Linear Feet per Minute] and Heat Sink Height 1
100 200
— 3.16
2.55 1.66
1.66 1.31
1.47 1.23
0.085"
2.235"
400 600 800
2.04 1.66 1.41
1.08 0.94 0.80
0.90 0.78 0.71
0.87 0.75 0.69
0.130"
1000
1.29
0.76
0.67
0.65
Height